Field of The Invention
The invention relates to a method of and apparatus for enabling the inhibition of television program display in dependence on the program content.
A law has been passed in the U.S.A. which requires that all television receivers having a display above a certain size sold from 1998, will have to have a means of enabling parents to prevent children from viewing coded programs containing violence, sex, and bad language. A so called "V-chip" is proposed which will monitor a code transmitted with the television signal and disable the television receiver when the code indicates forbidden program material, including scenes of violence, sex or other matter, which might be considered objectionable by some audiences or unsuitable for children.
In the U.S. V-chip system, the broadcaster rates each program in four censorship categories. The values for each category are then transmitted simultaneously as part of the extended data services (EDS) of the Closed Captioning (CC) system. The values are transmitted for as long as the program is on the air.
Using an access control mechanism, the parent sets a threshold for each category. If a rating exceeds the pre-authorized value, the V-chip suppresses the video and audio signals. As the reaction of the V-chip decoder is near instantaneous, the system can easily handle channel hopping. Moreover, the parent does not have to worry about missing content warnings in TV guides or at the start of programs.
The Electronic Industries Association (EIA) defines the four censorship categories and the number of data bits required to transmit the code:
MPAA rating (equivalent to film classifications, e.g., 18, PG, etc.)--3 bits PA0 violence content advisory level--2 bits (which allows for a scale of 0 to 3) PA0 sexual content advisory level--2 bits PA0 mature content advisory level--2 bits. PA0 i) establishing the authority of the user to define the program or parts thereof which are to be disabled, PA0 ii) entering into a memory within the television receiver, code words correspond to a program classification it is desired to suppress, PA0 iii) entering into the memory the time(s) during which the code words entered in step ii) are to apply, PA0 iv) entering into the memory, further code words corresponding to program classification it is desired to suppress, PA0 v) entering into the memory, further time(s) during which the further code words are to apply, PA0 vi) receiving television signals including code words representing the program classification, PA0 vii) comparing the received code words with the entered code words which apply at the time of reception, and PA0 viii) disabling the sound and/or visual display in dependence on the result of the comparison. PA0 ix) monitoring the teletext real-time clock to determine the time PA0 x) using the time determined in step ix) to select the code words stored for comparison with the received codes. PA0 xiv) monitoring the source of the received television signal, and PA0 xv) if the source is time shifted from the original transmission of the television signal so that the teletext real-time clock is not valid, either setting the comparison code words to those having the lowest level classification, or disabling the sound or visual display. PA0 xi) generating a real-time clock within the television receiver, PA0 xii) monitoring the real-time clock to determine the time, and PA0 xiii) using the time determined in step xii) to select the code words stored for comparison with the received codes.
The same principles apply to a system being field-tested in Canada but, at present, the two are not identical.
All American TV sets built after July 1993 had to include a CC decoder to provide subtitling. Current CC decoders (such as, the SAA5252 decoder sold by Philips Semiconductors) are capable of blanking out the TV picture when switched into full-text mode. They also have adequate display features to generate an OSD menu so that parents can program the censorship thresholds.
Unlike teletext, CC data can be recorded and reproduced by a VHS VCR during play-back of a program. Thus recorded and prerecorded tapes could also contain censorship data.
In Europe, the question of implementing a V-chip type system is altogether more complex than North America. The broadcasters are not regulated by a single government, and cultural and language differences mean variance in acceptable moral standards. Then, there are the technical issues of coping with a 625-line TV system that has little spare capacity for extra data signals.
The obvious solution is to use the American system but this has some disadvantages.
First, for broadcasters, the CC signal would occupy valuable teletext transmission capacity (one line would be permanently lost) and different encoding systems would be required.
Secondly, it would be very expensive for broadcasters in terms of the duplicate transmission equipment and data bridges (in cable amplifiers) required for both teletext and CC signals.
Thirdly, consumer electronics manufacturers would have additional overheads in providing teletext and CC decoding in every TV set and PC TV card.
Description of the Related Art
The concept of enabling a parent to control viewing of a television receiver using information transmitted by the broadcaster is not new and was proposed in International Patent Application WO83/02208 published on Jun. 23, 1983, corresponding to U.S. Pat. No. 4,605,964. In that document, it is proposed that a code be sent via the teletext signal transmitted with the television signal, the code being formed as a selected row number of a given teletext page. Thus, the page number and row number is transmitted in the field blanking period on the occurrence of a possibly offensive event. At the receiver, a teletext decoder is permanently set to look for the relevant page and identify the row number as and when transmitted. The particular row numbers indicated particular gradings of sound and vision events.
Various other means to convey the code have been proposed which involve the use of PDC signals and wide-screen signalling signals as disclosed in our co-pending UK Patent Application No. 9703192.6, corresponding to U.S. patent application Ser. No. 09/021,335, filed Feb. 10, 1998 (PHB34135).
All these arrangements require a parent, or other responsible person, to enter the appropriate codes into the television receiver and/or video recorder. Where a set is being used only by a child whose access to particular types of program is to be restricted, these codes can be entered and then no further action on the part of the parent is necessary. Where, however, different members of the family may be viewing the television set at different times of the day, the program classification appropriate for one member of the family may not be appropriate for other members of the family. This means that frequent entry of different classification codes may be required, and this imposes a considerable burden on the responsible person. For example, it may be necessary to reset the classification code to the lowest level every time the television set is switched off to ensure that material unsuitable for a child does not become inadvertently available. A consequence of this is that such a system may not be properly used unless the parent is extremely conscientious.